If they want to make money selling books or subscription services let them try on equal footing with other companies. They are actively attempting to grow their own ebook store and at the same time charging competitors an unavoidable 30% tax to sell on their platform.
Providing a store infrastructure on the phone is fine. Forcing application developers to use your api for in-app purchases is borderline. Disallowing any subscription based content to be viewed on the phone unless you get a shot at taking 30% is crooked, especially given the fact that they are in direct competition with some of those providers.
I understand big business. Apple desires to take a piece of every cash flow associated with a iphone from cradle to grave - whether they had anything to do with creating it or not. And why not? We're talking about a lot of money and the ability to diversify into the cashflows of businesses (journalism etc) they have nothing to do with. They are actively attempting to set up a toll bridge for all content consumed on mobile devices running their OS. They will probably succeed.
This may or may not end up being seen as legal. (I believe they are in a grey zone) I'm saying I don't believe it is moral. Apple didn't do anything to earn this money; they are simply trying to take it because it is there, and they can.
Apple is one of my favorite companies, it bugs me to see them acting this way. If MSFT were doing this sort of thing you'd have grabbed your torch and pitchfork long ago.